Various types of electromagnetic valves are available, usually comprising a casing, a coil, a fixed nucleus coaxial to the coil and a mobile nucleus subject to the action of the magnetic field generated by the coil; in particular, the mobile nucleus is influenced by an axial force of attraction exchanged with the fixed nucleus and moves between two separate working positions in which it interfaces with pneumatic connections, such as, for example, a powering position and a discharging position.
The solutions available present several disadvantages. For example, the mobile nucleus tends to stick inside the coil during its working stroke; moreover, the electromagnetic valves available are complex to assemble and the assembly operations do not always guarantee the necessary precision, with particular reference to the working stroke of the mobile nucleus.